You can find how many available Reward Points you have on a restaurant's menu page or their branded mobile app.
From a restaurant's menu page:
When on an ordering page, click on Login in the top right corner of the screen.
Follow the steps to login to your account.
Once logged in, click on the account icon in the top right corner of the screen and select Rewards.
From this page, you can see your total Reward Points and a list of items you can redeem!
From a restaurant's mobile app:
When on a mobile app, Click on the account icon in the top right corner of the screen and Login.
Once logged in, you can see your Reward Points total on the Home tab.
Click on the Rewards button to see your total Reward Points and a list of items you can redeem!
For more information, read this article: How does a guest use Reward Points?